A silicon chip implanted in the brain transmits thoughts to a computer cursor in real time, moving it with pinpoint accuracy on the screen, without an itch of the arm. Science fiction? Think again.

Stanford University researchers led by Indian scientist Krishna Shenoy have
developed what experts are hailing as the most advanced thought-controlled computer cursor created by man, promising to revolutionize digital access for the physically disadvantaged.

"These findings could lead to greatly improved prosthetic system performance and robustness in paralyzed people," Shenoy said. The team's work was published on Sunday in the journal Nature Neuroscience.

Though the country became officially polio-free earlier in 2012, 47500 new cases of Non Polio Acute Flaccid Paralysis (NPAFP) - associated with the oral polio vaccine used in the country - were reported just in 2011. Several other neurological injuries and diseases can also trigger paralysis in the limbs.

Though a paralyzed person cannot move an affected limb, cells in the part of the brain that controls movement get activated whenever he or she imagines moving that limb. Scientists have over the past few years tried to develop sensors that can be implanted in the brain to measure signals from individual neurons. These signals are then decoded to understand the thoughts, which are then used to control computer cursors.

But till now, all these efforts in the new field of neural prosthetics have involved a lag between the person's thoughts and the movement of the cursor, because they have relied on first recording brain signals and then decoding and acting on them.

The Stanford scientists decoded the brain signals and implemented them in real time - allowing rhesus monkeys used for the experiments to move cursors with their thoughts almost as fast as an arm would move them using a mouse.

"These exciting innovations should lead to a significant boost in the control of neuro-prosthetic devices and increase the clinical viability of this technology," said Jose Carmena, associate professor of electrical engineering and neuroscience at the University of California Berkeley and unconnected to the Stanford research.

The new model - known as ReFIT is also superior to earlier versions developed by other scientists in its ability to avoid errors like overshooting the point on the screen where the cursor is to be moved.

And unlike other models that tend to decay with time, the implanted brain chips used by Shenoy and his team have shown consistent performance over four years.

Though their current research focused on controlling cursor movement with thoughts, creating robotic limbs for paralyzed people using ReFIT is not impossible, said Vikash Gilja, who is a part of Shenoy's team along with bioengineering doctoral candidate Paul Nuyujukian.

"We think we have a very good chance of giving them something useful," Gilja said.